The point is if something looks too polished people assume that polish is all the way. You look at a polished chart different from a sketch. If I show you a napkin sketch of some new idea I have you understand it is new and not well thought out, thus you ask is the big picture idea correct. If instead the same idea is well polished in full color you think the big picture is correct and start looking at details that might need some adjustment. Depending on what sort of feedback you want, you need different types of drawing.